226 Transactions.—Zoology. 
behind them, just as a:dog does when scratching out a rat-hole. Günther 
objeets to the belief that they burrowed, because he says their fore-limbs 
are slender; but the skeletons in the Colonial Museum show that they are 
not very slender, and are certainly strong enough and stout enough to be 
used for burrowing in loose soil. The long sharp claws too are admirably 
adapted for penetrating deep into loose sand or light loam. The claws are 
sharply carved out on their posterior aspects. They soon become blunted 
when used against the wooden or tin walls of a cage. The dorsal spines 
are no hindrance when entering holes, because they are very soft, being 
easily bent on themselves or pressed down on one or other side. 
Locomotion. 
Dr. Günther elaborately described the abdominal ribs, and, speculating 
on their use, inferred that their special function was “to assist in locomo- 
tion.” He thought that by being approximated these ribs would assist the 
animal in erawling over rocks, especially as to each of the ribs (twenty-five 
or twenty-six in number) was attached a row of scales, the ends of which, 
he thought, were tilted up, thus causing a roughened abdominal surface, 
whieh would also help the animal. When dissecting a tuatara, it seemed 
to me that the amount of approximation between the ribs must be 
infinitesimal, and therefore these ribs could not be subservient to the 
special function of assisting in locomotion. I therefore carefully studied 
the motions of living tuataras, to ascertain which view was correct. 
Tuataras are very lazy in all their movements, and even when frightened 
they move very slowly. Their usual pace is a very slow erawl, the abdomen 
and tail trailing on the ground. The femora are articulated at right-angles ` 
with the pelvis, and the tibie and fibie at right-angles tothe femora ; this mode 
of articulation causes a great strain on the muscles of the posterior limbs, 
therefore when at rest the trunk rests on the ground. I tried many experi- 
ments with mine and narrowly watched their movements. When driven 
fast, or when chasing prey, they always lift the whole trunk off the ground, it 
does not touch atany spot. This rapid gait is very “ wobbling,” something 
like a man swimming sideways. After running three or four yards they 
grow weary and stop. They cannot jump the smallest obstacle, their limbs 
being too feeble. In ordinary crawling they propel themselves by means of 
their limbs alone, and the abdominal ribs take no part in these movements, 
though trunk and tail rest on the ground. The abdominal ribs are not used 
during either slow or rapid movements, the limbs doing all the work; the 
limbs are quite strong enough to drag the body and tail along the ground, 
and during more rapid but very brief movements are powerful enough to 
. lift the body and great part of the long heavy tail off the ground. 
If a tuatara be lying with its abdomen across the edge of a plate 
a 
: 
E 
